The present invention relates to an electronic device capable of preventing electromagnetic waves from being radiated outside, in particular, to an electronic device having an electronic component placed in a recess formed in a metal substrate, and a method for manufacturing the electronic device.
Recently, the large scaled integrated circuit (LSI) is increasingly improved to obtain a higher integration degree and higher processing speed. With this improvement, a delay in a signal due to a package and a printed circuit board having the package thereon becomes significant when the LSI is packed in the package.
A multi-chip module (MCM) is available to cope with above-mentioned problem. In the MCM, a plurality of chips, such as LSIs, ICs, resistors, capacitors, etc., to be connected to each other are placed to each other as close as possible. The placement reduces the amount of delay due to the package and assures high-speed feature of the entire MCM.
The MCM is used in a variety of apparatuses including a cellular or mobile phone.
Some people are concerned about the effect of electromagnetic waves on the human body generated by a semiconductor device in an apparatus such as a cellular phone that is typically used in close vicinity of the human body. Such an apparatus employs a shield structure that prevents electromagnetic waves from being radiated from within the apparatus body to the outside. However, it is extremely difficult to completely block the electromagnetic waves even if the body of the apparatus employs the shield structure. In practice, the electromagnetic waves generated in the semiconductor device probably leak out of the apparatus.
On the other hand, within the apparatus, the electromagnetic waves emitted from the electronic component (chip) may cause another electronic component to malfunction. Accordingly, these electronic components must be spaced apart from each other, and a compact design is difficult to implement. In the cellular phone, power required for transmission is substantially larger than power required for reception. If electronic components in the cellular phone are located close to each other, a transmitter section may cause an electronic component in a receiver section to malfunction because of the large power for transmission. It is thus difficult to realize the transmitter section and the receiver section in an MCM in the cellular phone.
There is a need for an electromagnetic shield structure that shields the electronic components from the electromagnetic waves in the semiconductor device such as the MCM. Alternatively, there is a need for an electronic device that can prevents the electromagnetic waves form being radiated outside.